A new model: radiation and cigarette smoke promote an aggressive cell phenotype and gene signature in head and neck cancer cells. and gene signature in head and neck cancer cells.

Background and purpose: Mucosal Head and Neck squamous cell cancers (HNSCCs) are aggressive invasive cancers. They arise in the oral cavity, oropharynx, nasopharynx, hypopharynx and larynx. To control local disease, radiation is used curatively and palliatively to destroy or reduce the tumour load. Smokers are at increased risk of developing these cancers, and smoking whilst receiving radiation worsens survival rates. However, the cellular and molecular mechanisms underlying this has not been well described. We developed a model to elucidate the effects of radiation and smoking and the pathways involved. This will enable the identification of novel pharmaceutical targets for patient trials. Materials & Methods: FaDu hypopharyngeal cancer cells were subjected to a fractionated daily radiation procedure and cultured in smoke exposed media. Cells were examined for changes in tumoursphere number, proliferation, migration, invasion, CD44 and ALDH1 expression, and next generation sequencing was performed. Immunohistochemistry compared CD44 and ALDH1 expression in never-smokers and smokers. Results: Radiation and smoking separately reduced FaDu Cancer Stem Cell (CSC) number and proliferation, and increased cell migration and invasion. Combined they further reduced CSC number and proliferation, and promoted migration. Through sequencing radiation and smoking produced a unique gene signature related to cell invasion, angiogenesis, and survival. CD44 expression and ALDH activity decreased after co-treatment and their expression did not associate with smoking status in a small patient cohort.